Quaternary ammonium salts of esters of salicylic acid as rust inhibitors

ABSTRACT

QUATERNARY AMMONIUM SALTS OF ESTERS OF SALICYLIC ACID ARE USED AS RUST INHIBITORS IN HYDROCARBON OIL.

United States Patent 3,652,644 QUATERNARY AMMONIUM SALTS OF ESTERS OF SALICYLIC ACID AS RUST INHIBITORS Elizabeth L. Fareri, Pittsburgh, Robert J. McGuire, Monroeville, and Harold O. Strange, Penn Hills Township, Allegheny County, Pa., assignors to Gulf Research & Development Company, Pittsburgh, Pa.

No Drawing. Original application Aug. 2, 1965, Ser. No. 476,717, now Patent No. 3,433,607, dated Mar. 18, 1969. Divided and this application Apr. 1, 1968, Ser.

Int. Cl. C07c 101/42 US. Cl. 260-471 R 4 Claims ABSTRACT OF THE DISCLOSURE Quaternary ammonium salts of esters of salicylic acid are used as rust inhibitors in hydrocarbon oil.

This application is a division of Ser. No. 476,717, filed Aug. 2, 1965, now Pat. No. 3,433,607.

This invention relates to chemical compounds and to compositions containing said compounds.

The chemical compounds of this invention are quaternary ammonium salts of esters of salicylic acid. These compounds have been found to exhibit high activity as rust inhibitors when present in a minor concentration in a hydrocarbon oil, such as fuel oil. The compounds of this invention are particularly eifective rust inhibitors when present in a hydrocarbon oil which is in contact with a water phase or is otherwise in a condition conducive to rust formation.

The quaternary ammonium salts of esters of salicylic acid of this invention can be selected from compounds having the general structure wherein:

R is a normal or iso alkyl, normal or iso alkenyl, aralkyl or cycloalkyl substituent containing 1 to 22 carbon atoms and can be substituted with substituents such as nitrogen, phosphorus, sulfur or oxygen,

R may be absent or is a normal or iso alkyl, nor-mal or iso alkenyl, aralkyl or cycloalkyl substituent containing 1 to 22 carbon atoms and can be substituted with substituents such as nitrogen, phosphorus, sulfur or oxygen.

"ice

R,,, R R and R, are each a normal or iso alkyl, normal or iso alkenyl, aralkyl or cycloalkyl substituent containing 1 to 22 carbon atoms which can be substituted with substituents such as oxygen, nitrogen, phosphorus, or sulfur, at least one of said groups containing at least four carbon atoms,

N is nitrogen and can be the nitrogen of a heterocyclic nitrogen-containing ring such as imidazoline, pyridine, thiazine or piperazine, in which case 'R and R are members of the heterocyclic ring and at least one of the substituents R and R contains at least four carbon atoms,

C is carbon, and

O is oxygen.

Although R R R and R generically encompass oxygen-containing substituents, compounds wherein R R R and R are hydrogen substituents which are free of hydroxyl groups with or without an ether polymer thereof unexpectedly possess dilferent utility from compounds wherein R,,, R R, and R have an hydroxyl group with or without an ether polymer thereof, and the latter group of compounds is covered specifically in application Ser. No. 476,666, filed Aug. 2, 1965, now Pat. No. 3,419,- 366.

Preferred compounds of this invention include quaternary ammonium salts of octyl, dodecyl, tridecyl or hexadecyl salicylates where the quaternary ammonium group is selected from the following:

Alkyltrimethylammonium wherein the alkyl group is a C to C substituent; dialkyldimethylammonium wherein the alkyl groups are C to C substituents; or mixtures of said monoalkyltrimethylammonium and said dialkyldimethylammonium groups.

Some commercial starting materials which can be utilized as the quaternary ammonium base are Arquad C, Arquad S, Arquad T, Arquad 12, Arquad 18, Arquad 2C, Arquad 2S, Arquad 2HT, Arquad T-2C, and Arquad S- 2C, all of which are commercial products. Arquad C, Arquad S, Arquad T, Arquad 12, and Arquad 18 are alkyltrimethylammonium chlorides wherein the symbols C, S and T indicate that the alkyl substituent comes from coco, soya bean oils or fats, or tallow, respectively, while in A'rquad 12 and Arquad 18 the alkyl substituent is essentially pure dodecyl or octadecyl, respectively. Arquad 2C, Arquad 2S and Arquad 2HT are dialkyldimethylammonium chlorides wherein the alkyl substituent is coco, soya' and hydrogenated tallow, respectively, and Arquad T2C and Arquad S-2C are mixtures of the indicated alkyltrimethylammonium chlorides and dialkyldimethylammonium chlorides.

Salicylic acid is a convenient starting material in the preparation of the quaternary ammonium salicylates of this invention. Salicylic acid contains an hydroxyl radical and a carboxylic acid radical at ortho positions on a benzene ring. In preparing the quaternary ammonium salts of this invention, the reactant containing the quaternary ammonium cation is reacted with the hydroxyl radical of the salicylic acid rather than with the carboxylic radical so that the salt formed is a quaternary ammonium phenate rather than a quaternary ammonium carboxylate. However, the carboxylic acid radical is considerably more acidic and therefore more reactive with the quarternary ammonium cation than is the hydroxyl radical and in order for the quaternary ammonium cation to react with the hydroxyl radical rather than with the carboxylic acid radical the salicylic acid must be esterified prior to the reaction thereof with the quaternary ammonium compound. Therefore, the preparation of the quaternary ammonium salt of this invention is a two-step process in which the order of performance of the steps is critical, i.e. the salicylic acid starting material is first esterified by reaction with an alcohol and only after esterification is it converted to a quaternary salt.

In the following specific example for the preparation of the compounds of this invention from salicylic acid, the more reactive carboxylic acid radical is first reacted with an alcohol to form an ester. Thereupon, a commercial quaternary ammonium chloride is converted to the corresponding quaternary ammonium hydroxide. The quaternary ammonium hydroxide is then reacted with the hydroxyl radical of the ester of salicylic acid to form a quarternary ammonium salt of salicylic acid ester.

EXAMPLE Step 1.Preparation of isooctyl salicylate from salicylic acid A mixture containing 900 grams of salicylic acid, 1300 grams (10 moles) of isooctyl alcohol, 30 grams of ptoluenesulfonic acid and 1000 milliliters of toluene was heated at reflux in a -liter flask fitted with a Dean and Stark trap. Reflux was continued until no more Water collected in the trap. The solution was cooled to room temperature and extracted with one liter of water, then with one liter of percent sodium bicarbonate solution followed by a washing with one liter of water. The extracted solution was dried over anhydrous sodium sulfate, filtered and vacuum-distilled. After distillation of toluene and excess isooctyl alcohol, 1568 grams of a clear oil was collected at 150-l-60 C. and 3.2 millimeters presssure. Analysis of the product showed 72.21 percent carbon, 8.90 percent hydrogen, 18.21 percent oxygen and a molecular weight of 265. Theoretically, isooctyl salicylate contains 71.9 percent carbon, 8.8 percent hydrogen, and 19.2 percent oxygen, and has a molecular weight of 250.

Step 2.Preparation of di(hydrogenated tallow)dimethylammonium isooctyl salicylate from isooctyl salicylate Ninety grams (0.154 mole) of di(hydrogenated tallow) dimethylammonium chloride as a 75 weight percent paste containing isopropanol and a small amount of water, was dissolved in 200 milliliters of benzene. The composition of the 75 weight percent of the paste which consisted of di(hydrogenated tallow)dimethylammonium chloride was 75 percent by weight distearyldimethylammonium chloride, 1 percent by weight dioctadecenyldimethylammonium chloride, and 24 percent by weight dihexadecyldimethylammonium chloride. With stirring, a warm solution containing 10.1 grams (0.153 mole) of potassium hydroxide (assay 85%) in absolute ethanol was added to the benzene solution. The precipitated potassium chloride was removed by filtration. To the filtrate was added 38.4 grams (0.153 mole) of isooctyl salicylate. Solvent was removed. The product, a brown oil which solidified on cooling, contained 1.81 percent of nitrogen. The calculated nitrogen content of di(hydrogenated tallow)dimethylammonium octyl salicylate is 1.75 percent.

Tests were conducted to illustrate the high rust arresting effectiveness of the compounds of this invention as compared to a control fuel oil sample without additives and as compared to a control fuel oil sample containing calcium octyl salicylate. In conducting these tests, a test solution was prepared by placing a mixture of 80 percent by volume of fuel oil or fuel oil plus additive with percent by volume of distilled water into a 4-ounce jar and shaking vigorously for one minute. A clean specimen of SAE 1020 steel was immersed nearly vertically into 4 each test jar and the jar was stored at room temperature. The steel specimens were inspected and rated after 1 day, 3 days and 7 days, respectively, and the results of the inspection are shown in the following table. A rating of 0 signifies no rust; l signifies 1 to 5 percent of the surface area rusted; 2 signifies 6 to 25 percent of the surface area rusted; 3 signifies 26 to 50 percent of the surface area rusted; and 4 signifies greater than 50 percent of the surface area rusted. The results of the tests are presented in the following table.

1 Heavy red and black corrosion where water droplets cling to or creep over portion of steel specimen in the fuel 01113112159.

h Typical fuel oil inspections:

Gravity: API, ASTM D287 Viscosity SUV; See, ASIM D446, F. Flash, P-M: F., ASTM D93 ,A-sTM D97 2a Distillation, ASTM D158:

Over point: F. End point:

10% lat: F.

It is seen from the above table that in the test with the fuel oil control sample without additives and in the test with the fuel oil control sample plus calcium isooctyl salicylate there was rusting over more than 50 percent of the surface area of the steel specimen in the Water phase and also heavy corrosion in the steel specimen in the fuel oil phase where water droplets clung to or crept over the portion of the specimen in the fuel oil phase. In contrast, the table shows that in the test with the fuel oil sample plus di(hydr-ogenated tallow)dimethylammonium isooctyl salicylate there was rusting over only 1 to 5 percent of the surface area of the steel specimen in the water phase, while there was no rust in the portion of the steel specimen in the fuel oil phase.

The quaternary ammonium salicylates of this invention are oil soluble and can be present in hydrocarbon oils over a wide range of concentrations. For example, they can be generally present in hydrocarbon oils over a concentration range of about 0.002 up to about 10 percent by weight, the higher region of the range being especially useful when preparing a concentrate, or preferably, over a concentration range of about 0.005 to about 0.1 percent by weight. Although useful in a wide variety of hydrocarbon oils such as gasoline, jet fuels, diesel fuels, etc., the quaternary ammonium salicylates of this invention are especially useful in fuel oils, such as blends of straight run and catalytically cracked fuel oils. Also, the compounds of this invention are primarily useful for rust inhibition in oils which are in contact with an aqueous phase.

Various changes and modifications can be made without departing from the spirit of this invention or the scope thereof as defined in the following claims.

We claim:

1. A quaternary ammonium phenate-type salt of octyl, dodecyl, tridecyl or hexadecyl salicylate wherein of the four groups on the quaternary ammonium radical two or three are methyl groups and the remaining are derived from coco, soya bean oils or fats or tallow.

6 2. A quaternary ammonium phenate-type salt of octyl, dodecyl, tridecyl or hexadecyl salicylate wherein of the References Cted four groups on the quaternary ammonium radical two or Final, I. L. Organic Chemistry, volume one (1963),

three are methyl groups and the remaining are dodecyl pub. by LongmansLondon, page 318 relied on. or octadecyl groups. 5

3. The distearyldimethyl quaternary ammonium phe- LORRAINE WEINBERGER, Primary Examine?! nalte-type salt of octyl, dodecyl, tridecyl or hexadecyl L A THAXTON Assistant Examiner sa icylate.

4. The dihexadecyldimethyl quaternary ammonium Us Cl XR phenate-type salt of octyl, dodecyl, tridecyl or hexadecyl 10 salicylate 260-268 R, 294.8 G, 295 R, 302 R, 309.6, 470

*zg gg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,652,644 Dated March 28, 1972 E. L. Fareri, R. J. McGuire and H. 0. Strange It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 61, delete "R and substitute therefor R'- Signed and sealed this 29th day of August 1972.

(SEAL) Attest:

ROBERT GOTTSCHALK Commissioner of Patents FDWARD M.FLETCHER.JR.

Attesting Officer 

